Method and means of gas distribution in inlet manifolds for internal combustion engines



Aug. 27, 1935. J. A. H. BARKEIJ 2,012,902

METH BANS OF GAS DISTRIBUTION IN INLET N ENGI OD AND M MANIFOLDS FOR INTERNA OMBUSTIO Filed July 1934 Sheets-Sheet 1 INVENTOR Aug. 27, 1935. A BARKEIJ 2,012,902

METHOD AND MEANS OF GAS DISTRIBUTION IN INLET MANIFOLDS FOR INTERNAL COMBUSTION ENGINES.

Filed July 18, 1954 s Sheets-Sheet 2 FIG 2 c Q FlGZ).

Aug. 27, 1935. J. A. H. BARKEIJ 2,012,992

METHOD AND MEANS-OF GAS DISTRIBUTION IN INLET MANIFOLDS FOR INTERNAL COMBUSTION ENGINES Filed July 18, 1954 3 Sheets-Sheet 3 I !N\IENTOR Patented 27, 1935 LIETHOD AND MEANS OF GAS IHSTRIBU- TION IN INLET MANIFOLDS FOR INTER- NAL COMBUSTION ENGINES I Jean A. H. Barkeij, rlltadena Galif. Application July 18, 1934, Serial No. 735,837

v27 Claims. (or. 123- 2) My invention relates more particularly to the lies or may lie below the manifold belonging to distribution of a fuel-air mixture to the cylinders cylinders l, 4, 6,! (inside numbering) of a V type motor, having two rows of cylinders Fig. 2B shows the same arrangement for a at an angle, or a multiple of two rows. down-draft carburetion; It is, of course, under- I The present application is a continuation in stood that the relative location of these two mani- 5 part of my application Ser. No. 101,715 of April folds may be reversed in position. 13, 1926, especially for the figures on the first and Fig. 2C is equivalent to Fig. 2 and shows merely second sheet of drawings. Those on the third that the distances from the fuel mixing meausto sheet, Fig. 5 and 6 are new. It is at the same time the cylinders can be equalized, and that both a continuation in part of my application No. manifolds can be cast in a single unit. 10 632,006 of Sept. 7 1932 and of my application No. Figs. 3 and 4 show double manifolding and car- 702,970, of Dec. 18, 1933. buretion like Fig. 2. Figs. 5 and 6 show another The sequence of the suction periods, which are type of double manifolding and double carbure-' substantially greater than 180 but not greater tion. Each group of four cylinders has four pri- 16 than 255 depends upon the arrangement of the mary passages from a primary zone of distribution 5 crank pins and the angle of the cylinder rows. and each group may have separate fuel mixing The first object of my invention is to arrange means, as already shown in Fig. 4, or may have the fuel-mixing means centrally between the two fuel mixing means in common as shown in Fig. 6. cylinder blocks, and to arrange the primary Each group of four cylinders, two in each block, 20 branches extending from the inlet passage or riser have a separate throttle but fuel mixing means in a (R) connected to said fuel-mixing means longicommon, as shown in Fig. 6. It is understood that tudinally with respect to the longitudinal axis of the arrangement of Fig. 6 may be applied on the the engine, which axis is parallel to the axis of the manifold of Figs. 2, 2C, or that of Figs. 3 and 4, and crankshaft thereof. r conversely. Referring to the figures in particular, 26 My second object is to arrange the manifolding in Fig. 1 the numbers inside the circles representand the sequence of the suction order, compatible ing the cylinder bores indicate the cylinders, the with the arrangement of crankpins and angle of numbers I to 8 outside said circles indicate in the cylinders, so that no two immediately consecuwhich order the said cylinders have their suction tive suctions occur in the same direction in the period sequence. 30 same primary branch of the manifolding. In Fig. 2 the same numbering for the cylinders My third object is to arrange dual or double and for the sequence of the suction periods is manifolding, which incorporates at the same time used. The cylinders I, 4,6, I are connected to one the said first and second object. manifold having fuel mixing means, the cylinders Other objects will appear hereafter during the 2, 3, 5, 8 being connected to the other manifold discussion of the various figures and objects. being pr with fuel mixing means- 35 Referring to the drawings, Fig. 1 represents dia Each manifold as three Primary c e grammatically the arrangement of the cylinders, Two o these a e a a g d lon t y of the i valves and manifolding of a V-type engine, havengme. branch A1 leadmg o cy der branch ing four cylinders in each cylinder block. The A2 cylmdels and branch A: to cylinder 1, manifolding in this figure is adouble or dual'manibranch A to cylmder branch A to cylinders 3 4,0

6 to cylinder 8. fold but fed by a single carburetor. branch A Fig. 1A represents diagrammatically the crank- 2A shows the mamfoldmg of 2 on the pin arrangement of the crankshaft used in said ig g g igggfg g iggggg g gg 32$? gg zgs is figg g z zys g g zz f 2g; I f olds are arranged one below the other, but if local curves where the passages cross each other, are glaces g i g wlthf h m' preferred they can be both substantially at the tai tng t e per ee 9. ance o e reciproca mg Same leveL m h th Par in Fig. 1A is shown a crankshaft, of w c e Fig. 2 represents" diagrammatically the same four crankpins to 4 are arranged in clockwise type of engine, having two systems of gas distribudirection L z 4 3 and seen from the other end tion, each system having a single separate carthe same crankpins are arranged I, 3,. 4, 2 as buretor. Fig. 2A shows Fig. 2 on the section line shown in Fig. 4, Of course, it understood that 2A-2A and shows that the inlet manifold besaid crankpins in Fig. 4 may be so arranged as 66 longing to cylinders I, 3, 5, 8 (inside numbering) shown but seen from the same end. Such a u I crankshaft causes perfect balance of the reciprocating parts in a v-type eight cylinderengine, as disclosed in Balancing of engines, 1907, By Archibald Sharp. or any other good book on engine balance, high speed engines.

Figs. 5 and 6 show a double manifolding in which the suction intervals of alternate again between the same two groups of Figs. 2, 3 and 4. In this arrangement however, each primary zone in each manifold has four branches going from the primary zone. immediately to the cylinders of the respective groups. The various branches are numbered A to A according to the numbering of the cylinders inside'the circles. The type of gas distribution here is identical with that for the group of cylinders I, 3, 5, 1 in Fig. 3 in which the immediate successive suctions in that group with intervals of alternate in direction in the two branches. Here these suctions with 180 interval alternate between the four branches of eachgroup of four cylinders. Therefore the gas distribution in this type of gas distribution is balanced for both groups of four cylinders, which is not thecase in the manifolds of Fig. 2 or 3 for both groups. The arrangement of Figs. 5 and-6 have, however, in common the feature that the various branches of the two manifolds are arranged substantially lengthwise and midway the two cylinder groups.

Like in Figs. 3 and 4 the two manifolds are arranged one above the other in order to arrange the eight branches so that they do not cross each other in the same plane. The branches of the upper cylinder will be therefore slightly longer than those of the lower manifold, but this difference is negligible. The inside surface of this manifolding is greater than those of Figs. 1, 3 or that of Fig. 2, but the advantage is that the gas distribution in both manifolds is more equalized than in any of the other types.

It is understood that folds have separate fuel mixing means, .but it is possible to lead gas from a single fuel mixing means into both separate manifolds, one for four cylinders having suction intervals of 180. .The advantage of such an arrangement would retain somewhat the advantage of the separate manifolding. This arrangement is shown above the double manifold in Fig. 6,.and may be considered as a double separate manifold though they possess in fact a single carburetor.

Fig. 3 shows the arrangement of a double manifolding and double carburetion resembling in some respects that of Fig. 2. However, as we will see later, even if the cylinders of the two blocks are grouped in two halves, each half having suction intervals of 180, it is possible to interconnect them in various ways, with the result that the actual gas distribution effected by said manifolding differs substantially from each other, retaining thereby the longitudinal arrangement of the primary branches.

In Figs. 3 and 4 one manifold connects again with the cylinders I, 4,0, 1 and the other manifold with cylinders 2, 3, 5 8.

Fig. 4 shows this manifolding of Fig. 3 on the cross-section line 4-4, and shows that one manifold may be conveniently arranged below the other, as shown in Figs. 2A and2B, for the arrangement of Fig. 2.

The cylinders I, 4, 6, I have suction intervals of 180 among each other and so has the group of cylinders 2, 3, 5, 8. The crankshaft of Figs. 3

'5 and 4 allow 8 different suction or firing orders in the two separate mani-' clockwise direction and a in anti-clockwise direction. Half -oi these firing'showever are undesirable as four cylinders fire consecutively .in one block and then four consecutively in the other block. g I

The gas distribution for oneof these more favorable suction orders as shown in Fig. 1 in numbering outside the circles, eifect the condition that-no two immediately consecutive suction periods occur in any of the six branches A to M. This arrangement effects therefore a perfectly balanced gas distribution.

Considering Fig. 2 with the same suction sequence, or that shown in Fig. 2, it appears that in each of the two manifolds the same condition occurs. For the first group of cylinders I, 4.5, 'I the suctionis either 1, 7, 4, 6 or 1, 6, 4, 7 so that two immediate consecutive suction periods are always in the same branch to cylinders 3 and 5, considering the suction periods for this group having an interval of 180. The same condition obtains for the group of cylinders 2, 3, 5, 8 of which the suction order is either 3, 5, 8, 2 or 5, 8, 2, 3. Two immediate consecutive suctions in this group of four cylinders occur to cylinders 3 and 5. Considering all the suction periods with an interval of 90, the immediate consecutive suction periods are alternately in the said two groups.

In the arrangement of Figs. 3, 4, taking the same suction sequence as that shown in Figs. 1 and 2, it appears that the suction periods in the left manifold to the left but centrally between the cylinder blocks connected with cylinders I, 4, G, I do not alternate in the two branches thereof (see primary zone P and branches A and A However in the right manifold (P and A and A) the suction periods for this manifold do not alternate in direction from the primary zone. Therefore the gasdistribution is perfectly balanced for the manifold and primary zone P, but not for the manifold and primary zone P Therefore the actual condition of gas distribution in these two types of double manifolding are different.

It would be also possible to connect the cylinders 4 and 6 with one branch and the cylinders I and I of the first group of four cylinders with the second branch of one manifolding and carburetion, and equally the cylinders 3 and 5 with one branch and cylinders 2 and 8 with another branch of the second manifolding and carburetion. In this case, these branches would be transversed to the longitudinal axis of the engine, and not centrally between the two blocks, and such arrangement would abandon the fundamental arrangcment of all manifolds shown, to arrange the primary branches longitudinally and centrally of the engine. In the arrangement of Fig. 2 is a slight deviation in so far as two primary branches are transverse. However, this manifolding is substantially arranged longitudinally and centrally of the engine, as the other transverse arrangement just discussed cannot be so arranged that the gas distribution of Fig. 2 or Fig, 3 can be incorporated therein and be at the same time longitudinally arranged. Therefore the type of gas distribution is inherent to the arrangement longitudinally and centrally between the two cylinder block's.

Nevertheless in all the arrangements shown the primary zones with the primary branches are arranged longitudinally between the two cylinderblocks, which arrangement has considerable advantages not only for the eight cylinder V-type but also for the 12 and 16 cylinder V-type.

Modifications in detailsmay be made and therefore I do not wish to be restricted to the specific forms herein described except as required by the language of the claims in view of the prior. art. except for the arrangement of Fig. 2. in which the distribution of gases is perfectly balanced for the two groups of cylinders, and the condition of both being perfectly equal to each other. and except the arrangement of Figs. '1, 8, in which the gas distribution is nearly balanced.

It is to be noted that for the firing sequence for the crank shaft of Pigs. in and (or) 13 that there is always in any firing order, a single pair of immediately successive firings in two adjacent cylinders at one end of one block.

The cylinders in each block are shown exactly opposite each other in the same transverse planes, but it is supposed that the cylinders may be staggered to accommodate two connecting rods of two opposite cylinders side by side on the same crankpin. If it is preferred to hinge said connecting rods over each other on the same crankpin, the cylinders can be arranged exactly opposite each other.

Each cylinder is shown with an inlet and an exhaust valve, and for the manifold arrangements shown, either one of the two may be chosen as the inlet or as the exhaust valve.

Repeating the main features of the three types of manifolding shown, it appears that in the first type of Fig.2 (or 2C) the gas distribution in both manifolds is substantially the same. In the type of Fig, 3 they differ in the two manifolds, while in the type of Figs. 5 and 6, the gas distribution is again the same in both manifolds, but it differs from the arrangement of Fig. 2 (20) in that the successive suction periods in each manifold with an interval of 180 are successively always in another branch.

In all three types the suction intervals are with 180 in each manifold, and the immediately successive suction periods with an interval of 90 alternate between the said two manifolds. In all figures the inlet valves of two adjacent cylinders at one end of one block are adjacent to each other. The result is that in all three kinds of manifolding the distances from the carbureting means to all the cylinders is substantially the same.

When in the following claims is spoken of the adjacent inlet valve of a cylinder, it is meant that the two valves of every pair of adjacent cylinders at one end of one block, which are adjacent to each other, are the inlet valves.

The valves are all shown btside the cylinder block, but they may be placed in the cylinder heads if desired.

In all arrangements the carbureting means are placed centrally between the two cylinder banks,

and all three types of manifold are arranged substantially lengthwise the engine instead of transversely thereof.

If in the following claims is spoken of an outer cylinder, either cylinder I, 2, I or 8 (inside'numbering; is meant. If is spoken of an inner cylinder either cylinder 3, 4 5 or 6 is meant. If is spoken of the nearest inner cylinder, the cylinder 3 opposite cylinder 2 is meant, or the cylinder 5 opposite 8, or the cylinder Ii opposite I, or the cylinder 4 opposite i, and conversely (see inside numbering).

The outside numbering refers to a preferred firing sequence. These numbers have to be discerned rigidly to prevent confusion.

It is understood that when the two systems of ture tothe end cylinders of one block and passages, .jone for each group'fof "four cylinders,

are fed by a single carburetor with a single jet that the advantages, obtained otherwise by feedingv each system witha separate fuel jet, are still somewhat present and su'cha'construction would fall clearly under theifollowin'g claims.

It is likewise understood that the two fuel jets .block, with another" branch to the other outer cylinder of thesaine block, a third-branch to intermediate two cylinders of the other block, a second system of passages of which two similar separatebranches extend to the outer cylinder of the other block and to the intermediate, cylinders of said first block.

2. The combination with an eightcylinder V- engineof the type inwhich two cylinders at onef. end;of one blockfire'in immediate succession and carbureting means therefor of manifolding means including Ia primary zone having three primary branches, two of said branches extending to the outercylinders of one block, the third branch extending to the intermediate cylinders of the other block, a secondprimary zone having three primary branches, two of said latter branches leading to the outer cylinders "of said other block, the third'of said latter branches leading to the intermediate cylinders of said first block.

3. The combination with an eight cylinder V- engine having four cylinders in each block and carbureting means therefor, of manifolding means comprising two systems of passages, each system arranged to supply fuel mixture to end cylinders of one block and the intermediate cylinders of the other block, said'engine having a suction sequence so that no two immediate successive suction periods occur inleither one of said system of passages, said systems ofpassages being arranged lengthwise midway the said cylinder blocks. q

4. In an eight cylinder V-type engine having two immediately successive suction periods in two adjacent end cylinders of one block, a double,

system'of manifolding and carburetion, each system being composed of a riser leading to a primary zone of distribution, three primary branches extending from said zone to the cylinders of each group of four cylinders. l

5. In an eight cylinder vtype engine having two immediately successive suction periods 'inthe:

y be fed frorn' a single ,fioat chamber, as is well known in theart."

6. The combination with anfeight cylinder V-' engine having four' cylindersin each =block-and carbureting means therefor, of manifolding means comprising two separate systems of passages, each system arranged to supply fuel mixintermediate cylinders of the other block, each the manifolding system being arranged lengthwise and midway between said two cylinder blocks the distances from said carbureting means to said cylinders being substantially the same for each system and the same for both systems.

7. The combination with an internal combustion engine of theeight cylinder V-type having four cylinders in each block and having a firing order such that two adiacent cylinders in one block fire in immediatesuccession, of manifolding means comprising two separate systems of passages, each; plying mixture to four cylinders. one of adjacent cylinders receiving fuel mixture from one ofsaid systems and the other cylinder receiving mixture from the other system, said means being arranged lengthwise between said two cylinder blocks, the inlet valves of each pair of adjacent 'cylinders. at one end of one block being adJiijcentHtoeach other, each separate system connecting"with onev inlet valve of said pairs of adjacent cylinders, the 'distances from the inlet of each manifold to :thevalves of each separate system being substantially the same, said two systems of passages combined with a suction order so that the consecutive suction periods in one system alternate in direction froma primary zone of distribution therein. while theconsccutive suction periodsin the :other system do notalternate for the consecutive suction periods insaid other system from a primary zone of distribution therein.

8. In a v'- e'ight cylinder engine of the type in ahich two adjacent cylinders at one end of one block of cylinders'ifire in immediate succession,

. a double manifolding system, each system connecting with twogcylinders in one block and two cylinders in the other block, said cylinders belonging to one system having a manifold of which the distances from the inlet of said manifold to the cylinders of said system are substantially equal, the inlet valves of said cylinders being arranged in pairs adjacent to each other, each inlet valve of each pair belonging to one of said two systems.

9. In an eight cylinder engine of the V-type in which two adjacent cylinders at the end of one block fire in immediate succession, two separate inlet manifolds, one manifold with fuel mixing means having two primary branches extending in opposite direction from a primary zone of distribution therein, one branch thereof leading to a secondary zone of distribution with two secondary branches, one of said latter branches leading to the outer cylinder of one block and the other branch to the nearer inner cylinder of the other block, the other primary branch leading to another secondary zone having two secondary branches, one of said latter branches leading to the other outer cylinder of said first mentioned block and the other secondary branch leading to the nearer inner cylinder in the other block of cylinders, the other manifold having primary and secondary branches arranged in the same way as said first manifold, said manifolds combined with a crankshaft of which the crankpins are numbered successively from one to four from. one end to the other, the plane containing the crankshaft axis and crankpins I and 4 being angularly spaced at right angles from the plane containing the crankshaft the consecutive suction periods in each manifold having an interval of 180", the consecutive sue-- axis and crankpins 2 and awe crankpin arrangement resulting in suction ortion periods in one manifold alternating in direction with an interval of 180 from said primary zone therein, the consecutive suction periods in the other manifold alternating in direction from said primary zone with an interval of 360.

10. In an eight cylinder engine of the V-type in which two adjacent cylinders at one end of one block fire in immediate succession, two separate inlet manifolds, and mixing means therefor, the cylinders in one block being successively numbered I. I, I, I and being respectively located substantially opposite to those cylinders successively numbered 2, l, I, I in the other block, one inlet manifold connected with a primary zone of distribution having two primary branches one of said branches being connected with cylinders 2 and 8, the other branch thereof with cylinders 5 and I, the other inlet manifold connected with a primary zone having two primary branches one of said branches connected with cylinders i and I, the other primary branch thereof with cylinders i and 1.

11. In an eight cylinder engine of the v-type, in which two adjacent cylinders at one end of one block have immediately consecutive suction periods, an intake manifolding system composed of two separate inlet manifolds, one manifold including a passage leading from the carbureting means to a cylinder at the end of one block and an intermediate cylinder of the other block and another passage leadingto an end cylinder of said first block and'an intermediate cylinder of the other-block, said manifold having suction periods with an interval of substantially 180.

- 12. In a V-eight cylinder engine, in which two adjacent cylinders at one end of one block fire in immediate succession with an interval of 90, an intake manifolding consisting of two separate manifolds with separate fuel mixing means. one manifold having two branches each of said branches connected with a single cylinder in each block,, the other manifold having equally two branches each of which is connected with only one cylinder in each block, each manifold having suction intervals of substantially 180.

13. Ina v-eight cylinder engine, in which two adjacent cylinders at one end of one block fire in immediate succession with an interval of 90. an intake manifolding and fuel mixing means therefor, said manifolding including a passage leading to only one end cylinder in one block and another single inner cylinder in the other block.

14. In an eight cylinder engine of the V type, in which two adjacent cylinders at one end of one block have immediately consecutive suction periods, an intake manifolding system composed of two separate inlet manifolds, one manifold including a passage leading from the carbureting means to a cylinder at the end of one block and to the nearer inner cylinder of the other block and another passage leading to an end cylinder of said first block and to the nearer inner cylinder of the other block, said manifold having suction periods with intervals of substantially 180.

15. In a V eight cylinder engine inwhich two adjacent cylinders at one end of one block fire in immediate succession with an interval of 90, an intake manifolding and fuel mixing means therefor. said manifolding including a passage leading to only one end cylinder of one block and to the nearer inner cylinder in the other block.

is. In a v eight cylinder engine, in which two adjacent cylinders at one end of one cylinder block fire in immediate succession with an interbranch connecting with val of an intake manifolding consisting of two separate manifolds, each manifold connected with cylinders having a firing interval of carbureting means for said manifolds and the distances from the said carburetin means to the cylinders of both groups beingsubstantially the same, said manifolding arranged substantially longitudinally of said engine.

17. In a v eight cylinder engine having four cylinders in each block and immediately'successive firing in two adjacent cylinders at one end 1 of one block, two manifolds, each manifold composed of a single primary zone of distribution having four branches, two thereof leading to the end cylinders of one block and the other two to the inner cylinders of the other block.

18. In an eight cylinder engine of the V-type, in which two adjacent cylinders at one end of one block have immediately consecutive suction periods, two systems of passages, each system arranged to supply fuel mixture to the end cylinders of one block and the intermediate cylinders of the other block, said engine having suction periods with an interval of 90, the suction periods in each system having an interval of 180, each manifold having a primary zone of distribution and two primary branches extending therefrom, the suction periods in one system alternating in direction from said primary zone therein with an interval of 180, the suction periods in the other system alternating in direction from the primary zone thereof with an interval of 360.

19. In an eight cylinder engine of the V-type, in which two adjacent cylinders at one end of one block have immediately consecutive suction periods, having the cylinders whose firing orders are 2, 5, 7, 4 in one block and those whose firing orders are ,1, 8, 6, 3 in the other block, manifolding means for said engine comprising two sys tems of passages, one system arranged to supply fuel mixture to the cylinders whose firing order is 1, 3, 5, '1, and the other system supplying the cylinders whose firing order is 2, 4, 6, 8, said first system having a primary zone with two branches, one branch connecting with the cylinders having the firing order 1 and 5, the other the cylinders having a firing order of 3 and 'l, the firings in said first system alternating with respect to a plane transverse to the longitudinal axis of said engine midway the 4 cylinders of each block, said second system having a primary zone with two branches, one branch connecting with the cylinders having a firing order 4 and 6, the other branch connecting with the cylinders havin a firing order of 2 and 8, the firings in said second system not alternating with respect to said plane transverse of said engine.

20. The combination with an eight cylinder v-type engine in which two adjacent cylinders in one block fire in immediate succession and carbureting means therefor, of an intake manifolding system including a passage leading from the carbureting means to the end cylinder of one block and the nearer inner cylinder of the other block, the suction periods in said passage having an interval of 360.

21. I'he combination of claim 20, in which said manifolding system has another passage leading from the carbureting means to the endv-engine of the type in which two cylinders at one end of one block fire in immediate succession and carbureting means therefor, of manifoldmg means including one manifold-branch having suction intervals of 360, and another manifold- C; 6 branch having a suction interval of 180;

23. The combination as set forth in claim 22, in which the manifolding means include two systerms of passages, one of said systems having said first manifold-branch having suction intervals of 10 360, said other system having said other manifold-branch having a suction interval of 180.

24. In a V-eight cylinder engine having a crank shaft, a combination of two substantially separate systems of passages, each system having 15 fuel mixing means substantially independent of the other in so far as the actual mixing offuel and air isconcerned, each system of passages being in general form and shape substantially equal to the other so that each system consists 20 of a primary zone and two branches, each branch of each system connected with an end cylinder of one block and the nearer inner cylinder of the other block, said crank shaft having crankpins which are arranged substantially at 90, said 25 crankpins respectively numbered from one to four and being so arranged that crankpins I and 4 are at 180 and likewise crankpins 2 and 8, crankpins l and 2 being at a 90 angle, said crankshaft and said systems of passages being operatively 30 combined so that the suction periods in one of said systems are spaced apart 180 degrees of crankshaft rotation, thus providing a substantially balanced gas distribution therein, the other of said systems having suction periods spaced 35 apart at an angle of crank shaft rotation which provides an unbalanced gas distribution therein.

25. In a v-eight cylinder engine, in which two adjacent cylinders at one end of one cylinder block fire in immediate succession with an interval of 90, an intake manifold structure including two separate fluid conducting portions, each manifold portion being connected with a group of four cylinders having a firing interval of 180, carbureting means for said manifold portions 45 and arranged so that the distances from the carbureting means to the cylinders of both groups of cylinders are substantially the same, each of said manifold portions having a single primary zone of fluid distribution and four separate branches connecting said zone of fluid distribution to the four individual cylinders of its group.

26. In an eight cylinder engine of the V-type in which two adjacent cylinders in one block fire in immediate succession and having carbureting 55 means, an intake manifold system including a manifold having substantially oppositely extending branches connected respectively to the end cylinders of one block and a third branch extending substantially at right angles to said other 00 branches and connected with two intermediate cylinders of the other block, said manifold system also including another manifold having three branches arranged similarly to the branches of said first mentioned manifold and connected with the two intermediate cylinders of said first mentioned block and the two end cylinders of the second mentioned block.

27. In an eight cylinder engine of the V-type, 70 a manifold system including two separate inlet manifolds operatively associated with said engine, carbureting means for said manifolds, one manifold having a primary zone of distribution and substantially oppositely extending primary 7 branches connected with said primary zone of distribution, a secondary zone of distribution connected with one of said primary branches, two secondary branches connected with said secondary zone of distribution and respectively connected with an end cylinder of one block and the nearer inner cylinder of the other block, a second secondary zone of distribution connected with the other of said primary branches, a sec- 10 0nd pair of secondary branches connected with 

